Thread-cutting device.



H. L. FISHER.

THREAD CUTTING nnvm.

APPLICATION FILED JUNE 2, 1910.

Patented Mar. 30, 1915 mamw 1N VE N TOR.

WITNESSES:

UNITED STATES PATENT OFFICE.

HENRY L. FISHER, OF 'WAYNESBORO, PENNSYLVANIA, ASSIGNOR TO LANDIS MACHINE COMPANY, OF WAYNESBORO, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

THREAD-CUTTING- DEVICE.

Specification of Letters Patent.

Patented Mar. 30, 1915.

Application filed June 2, 1910. Serial No. 564,718.

To all whom it may concern:

Be it known that I, HENRY L. FISHER, a citizen of the United States, residing at \Vaynesboro, in the county of Franklin and State of Pennsylvania, have invented certain new and useful Improvements in lhread-(Jutting Devices, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to thread cutting devices and has for its" object the improvement of such devices in regard to both the chaser itself and the holding means therefor.

In my prior Patent No. 86%,964, granted September 3, 1907, and for the reissue of which I filed an application September 16, 1908, Serial No. 453,375 I disclosed and claimed a novel form of chaser having a ridged or serrated face, one of its sides beveled, and a portion of the back cut away to leave a lip or projecting edge oppositely beveled; and I also disclosed and claimed a form of dove-tail clamp of which one element was formed in the body of the holder by cutting away the same so as to leave a projecting lip with an oblique or under-cut face, and the other element formed as a separate clamping bar with a longitudinal flange on one edge to engage in a groove in the holder and a beveled or under-cut face on the opposite edge. The beveled edge and the opposite beveled lip on the chaser were received and held between the under-cut lip or edge on the holder and the beveled edge of the clamping bar, respectively, this bar being secured to the holder by screws. Such a construction produces the following results: (l) The entire inward thrust, that is to say the thrust exerted by the Work in entering the die head, is transmitted through the body of the chaser. to the solid abutment or lip on the holder; (2) any wear or inequalities in the chaser are taken up and compensated for when the clamping bar is forced down by its screws; 3) the projecting lip on the back of the chaser lying below the top edge thereof, the body of the clamping bar lies flush with or lower than the outer edge of the chaser, so that a thread can be cut close up to a head or other projecting part on the work; and (4) since the serrations and all of the longitudinal edges of the chaser are parallel, each chaser may be set up or adjusted independently of the others without affecting the accuracy of their tracking. This is very important, because it permits adjustment to compensate for breakage or wear in any chaser Without replacing the whole set at once in a die head.

In my prior application Serial No. 450,769, filed August 28, 1908, I have described and claimed an improvement on the construction of the patent, embodying the following features: (1) The holder is made separate from and interchangeable on the slide body; (2) the groove on the holder for receiving the flange on the clamping bar has a beveled 4 face, so that when the clamping bar is forced ranged so that the chasers when cutting are tangential to the work and when the die is opened or closed, the cutting edges approach or recede from the work on lines radial thereto.

My-present invention is in the nature of an improvement on the prior devices thus referred to, and its specific object is to produce a design in which the life of the chaser will be much longer than that of the regular threading chaser, and in which there will be more substantial means for holding and protesting the chaser, which of course results in a longer life.

The invention is adaptable to both bolt and pipe threading, and provides especially for certain difficulties heretofore experienced in pipe work, due to the custom in pipe mills of testing the welding of the pipe to a certain extent in the course of the threading operation. In such testing, it is quite frequent for pipes to open up while being threaded, with a consequent strain on the chasers. In the previous forms of ehasers and holding means this strain might result in a considerable percentage of loss both in breakage and in time consumed in resetting. WVith the present device, however, such breakage is impossible.

Briefly stated, my present invention comprises the same leading features or elements enumerated above, with additional features as follows: (1) Instead of being straight, my improved chasers are preferably curved in the arc of a circle the radius of which is greater than that of the work to be threaded; (2) while. the general form and mode of attachment of the chaser is the same, the clamping bar is provided with a lip which extends entirely over the body of the chaser, and the recess or cut-out portion of the holder is somewhat deeper than before, so as to give a perfectly solid support; (3) to permit the end of the chaser toenter the work, .the' overhang on the clamping bar is cut away at one end on the arc of a small circle concentric with the cutting circle, that is to say having its center in the axis of the die; .(4) in order to accommodate inequalities and take up wear, the holder is provided with a saw cut or recess extending partly through its bodyin a plane parallel to its clamping face, which permits a certain amount of self-adjustment, after which the parts are held rigid by pressure screws.

My invention is illustrated in the accompanying drawings in which Figure l is a face view of a die head with the parts all in position and a piece of work shown in section. Fig. 2 is an edge view of a chaser detached. Fig. 3 is a sectional view of the same chaser on the line 33 of Fig. 2, moving in the direction of the arrow. Fig. 4 is a detailed section of a part of the holder, and the clamping bar, with a chaser and the clamping screws in position. Fig. 5 is a similar section of the older form of clamping bar. F ig. 6 is a face view of a modified form in which the chaser and clamp are straight instead of curved. Fig. 7 is a sectional view taken on the line 77 of Fig. 6. Fig. 8 is a detailed section of the clamping bar detached from the other parts.

Referring to the drawings, and especially to Fig. 1, A, A, A and A are chaser holders mounted on the body of the die-head D for advance and recession to and from the These holders may be.

center thereof. mounted as slides, as described in my prior patent and application hereinbefore referred to, but I prefer to mount them with trunnions or pivots eccentrically on the diehead, so that they .will merely swing or turn in opening. The collar and opening for the pivot bolt are shown in the modified form in Figs. 6 and 7, but as this feature forms no direct part of the present invention I have not shown it in Fig. 1, and its illustration in the other figures is incidental only.- It should be observed also that I have not deemed it necessary to show the 'mechanism for opening and closing the die, and for holding the chasers in operative position during the cut. Such mechanism can be very readily supplied, and may be a, of irregular shape on three sides, and

curved in the arc of a circle on the fourth side. The radius of this are of curvature may vary somewhat, but in any event it is greater than that of the cutting circle,

in order that the heel a of the holder may not only clear the workbut may also clear the cutting end of the next chaser and holder. The curved face a is recessed as shown at a in Fig. 4, to receive the chaser, the bottom of the recess being beveled or undercut as'shown at a. In its upper face the holder has a groove a and is recessed at a to receive the curved clampingbar C. This clamping bar is shown in plan in Fig. l-, and in section in Figs. 4 and 8. Along its rear edge it has a curved and beveled fiange 0 adapted to fit the groove a in the holder. Along its front edge it has a similar flange c, oppositely beveled to engage the chaser, and extending out from its top is a flanged overhang 0 adapted to drop over the upper edge of the chaser. The clamp has a transverse saw cut or a recess portion 0 to adjust itself automatically to any inequalities in the chasers. After such' adjustment rigidity issecured by means of the thrust-screws c which are threaded into the upper part of the clamp and bear on the upper surface of the lower portion a. The chaser is shown detached in Figs. 2 and 3, being designated in general by the letter E. It is curved on a circle concentric with the arc of curvature of the holder as well as that of the clamping plate, between which it is held. On its inner face, i. e., that of smaller radius, it has parallel serrations or cutting teeth best shown in Fig. 3, at e. In its back it has a recess e with an undercut or beveled edge or lip e and the opposite edge of the body is beveled in its entirety,

as shown at 0 The extreme edge formed by the intersection of this beveledsurface and the curved surface of the back, is cut away all around to form a threaded surface 6* adapted to cooperate with an adjusting screw 8 in the body of the holder. This screw is set into a smooth recess of just suflicient length to receive it, and this recess is located with its center coinciding with the lowest edge of the recess a in the body, so that less than ninety degrees of the surface is exposed to engage the threads in the chaser. The clamping plate is secured upon the holder by means of screws 0.

It will be observed in Fig. i that the outer portion of the overhang c is formed as an obliquely inclined flange, the purpose of which is to engagethe correspondingly beveled portion or throat of the chaser, indicated at e in Figs. 3 and 4. This engagefall within the edge of the dove-tail abut-- -ment at.

In Fig. 5 I have shown a modified form of clamping bar without the overhang. In F igs. 6'and 7 I have shown the same parts as in the other figures, but with the chaser and clamping bar straight-instead of curved. Some features of the device can-be adapted to a straight form'aswe'll a-sa curved form, and I shall therefore framemy claimsto include both.

Having thus described-my invention, what I claim and desire to secure by Letters Patent of the United States is:

1. In a die head, a chaser holder having'a seat for a chaser, a chaser fitted to said seat and extending tangentially with respect to the work when in cutting position, and a clamp extending outside of said chaser and extending to and engaging the front thereof for substantially its entire length.

2. In a die head, a chaser holder having a seat for a chaser, a chaser fitted tosaid seat, and extending tangentially with respect to the work when in cutting position, and a clamping device secured on the side of the chaser away from the work, and extending over and engaging the same on its front edge throughout substantially its entire length, said clamping device being cut away adjacent the cutting edge of the chaser to provide a clearance for the free operation of the cutting edge upon the work.

3. In a die head, a chaser holder having an arc shaped seat, a chaser of corresponding shape fitted to said seat and extending tangentially with respect to the work when in cutting position, and a clamping device curved on the arc concentric with the arcs of the chaser and its seat, and engaging the chaser throughout substantially its entire length on the side opposite the cutting edge.

4. In a die head, a chaser holder having an abutment, a chaser adapted to rest on said abutment, and extended clamping means secured on the holder and projecting throughout its length over the upper edge of the chaser with an overhang or drop flange engaging the outer face thereof, substantially as described.

5. In a die head, a chaser holder having an oblique face abutment, a chaser having its lower edge inclined to rest on said abutment and dovetail clamping means secured on the holder having an overhang or drop flange with: an-oblique or beveled lower face engaging throughout its length over the upper edge and outer face of the chaser, substantially as described.

6. In a diehead a holder having an abutment), achaser .fitted to rest on said abutment, and dovetail clamping means secured to the holder and adapted to engage the chaser throughout two separate portions of its surface in different planes, substantially as-described.

7. In a die head a holder having an abutment,.a chaserfitted to rest on said abutment, and dovetail clainping means secured to the holder and adapted to engage the chaser along substantially parallel lines on two longitudinally extending and laterally separate inclined portions of its surface, substantially as described.

8. In a die head a chaser holder having an-abutment, a chaser adapted torest thereon,- having two outwardly beveled parallel separated surfaces, and clamping means secured on the holder and provided with parallel dovetail projections adapted to separately engage both said surfaces on the chaser, substantially as described.

9. In adie head a chaser holder having an abutment, a. chaser adapted to rest thereon, having two outwardly beveled parallel.

separate surfaces, and clamping means secured on the holder and provided with parallel projections adapted to separately engage both said surfaces on the chaser, together with means for producing relative adjustment of the projections on the holder, so as to insure proper engagement and com pensate for variations in the chasers, substantially as described.

10. In a die head, the combination of a chaser holder, a chaser resting thereon, and a clamp, said chaser having one edge beveled and a dove tail on the side opposite the beveled edge, and said clamp extending over the top of the chaser and engaging the beveled edge thereof, and carrying an adjustable lip to engage the dove tail, together with means for securing the clamp on the holder, sub-- stantially as described.

11. In a die head, the combination of a chaser holder, a chaser, and a clamp, said holder having an abutment to receive the chaser so as to form therewith one element of a dove tail, said chaser. having its opposite edges oppositely beveled, and an intermediate lip or flange forming a third dove tail element and said clamp having a pair of parallel dove tail elements, one extending over the edge of the chaser, and the other engaging said intermediate lip or flange, substantially as described.

12. In a die-head, the combination of a chaser holder, a clamp fitted thereto,'and a chaser having thread-cutting serrations on its face, said chaser and clamp lying parallel, a projection'on the clamp extending over the upper edge of the chaser engaging the same on its face or thread-cutting portion, and an adjustable lip on the clamp engaging a dove tail element on the back of the chaser, with locking means for the lip and means to secure the clamp to the holder, substan- 1 tially as described.

13. In a die-head, the combination of a chaser holder, chaser, and clamp, said clamp fitted-in a recess in the holder and adapted to engage the chaser on both its face and its back, whereby the clamp forms also a arallel or distance piece for the chaser, su stantially as described.

14. In a die head, the combination of a body, a chaser holder carried thereby having two seats, the first having an undercut inner wall and the second having a transversely inclined surface at its inner side, a chaser fitted to the first seat and a clamping de- I vice for the chaser fitted to the second seat,

said clamping device having a beveled surface engaging the inclinedflportion of its seat, whereby the clamping device is alined with respect to the'holder and in turn accurately ahnes the chaser in its seat.

. gaging the same at a an are shaped seat, a concentric are shaped chaser fitted to said seat and held thereby with its cutting edge extending tangentially to the work, a clamping device for the chaser, and an adjusting screw located at the back of the chaser adjacent the seat thereof, held by one of the parts and having threaded engagement with the other, said clamping device engaging the front edge of said chaser.

17. In a die head, a chaser holder having a curved seat, a concentrically curved chaser fitted with its back in said seat and resting against said holder, said chaser extending tangentially with respect to the work when in cutting position, an adjusting screw havingthreaded engagement with theback of said chaser, and clamping means engaging the chaser on its front edge.

18. In a die-head, thecombination of a chaser holder, a chaser and a clam said chaser having one beveled surface a uttin on the holder and two oppositely bevele surfaces for engagement by the clamp, and said clam having'its body slit and means on each 0 the separated portions toengage one of the said surfaces on the chaser, substantially as described.

19. In a die-head, the combination of a chaser holder, a chaser and a clamp, said on the holder and two oppositely beveled surfaces for engagement by the clamp, and said clam having its body slit and means on each 0 the separated portions to engage one of the said surfaces on the chaser, together with adjusting screws threaded into one-part of the clamp and engaging the other part, and locking screws passing through both parts of the clamp into'the holder, adapted to secure .the clamp and chaser thereto, substantially as described.

21. In a die head, a chaser holder having an abutment, a chaser adapted to rest on said abutment, and clamping means secured to the holder and extendin over the edge of the chaser to engage the ront face thereof, sald clamping means beingvcut away to form a throat opening and guide for the .cutting end of the chaser, substantially as descrlbed.

22. In a die head, a chaser holder having an abutment, a chaser adapted to rest thereon, a clamplng bar or plate extending over the top of the chaser throughout its length,

and means to secure said clamping bar to the holder, the parts being so arranged that the face of the chaser will be tangential to the cutting circle at its intersection therewith, and the clamping bar being cut out around said point of intersection in a circle concentric with the cutting circle, so as to expose the cutting end of the chaser while serving as a protection and work-guide therefor,

. 23. In a die head, a curved chaser with a beveled base, a serrated face, a clamping pro ection on its top, and screw threads formed along its back, in combination with a holder having clamping means to 006perate withthe clamping projection on the chaser and a feed screw fixed in position adjacent the cutting end of the holder tangential to the back thereof and adapted to engage the screw threads on the chaser, said he der and chaser being set with the cutting .end of the chaser tangential to a circle concentric with the center'of the die head, and

said feed screw serving to maintain its cutting position by adjustment throughout the ent1re life of the chaser.

24. A curved chaser for die heads having its cutting end and one end of its convex areas only, and screw threads on a line .con-

centric with the curve of the chaser, but lying entirely without the said clamping areas.

25. A curved chaser for die heads having concave and convex surfaces, one of which is provided with longitudinally extending serrations, said chaser for definite clamping areas of'its surfaces adapted for engagement by suitable. clamping means, and screw threads on the chaserformed on an axis 0011- centric with the curve of the cutting surface but lying entirely without said clamping areas.

- 26. In a die head, a die holder provided with two seats, a chaser fitted to the first seat and having 0 positely inclined surfaces, clamping means ttedto the second seat and having oppositely inclined extensions engaging o posed inclined surfaces on the chaser an on the second seat respectively.

27. A. chaser for die heads having longitudinal serrations for chasing screw threads and two oppositely inclined complementary clamping surfaces, one on the edge of the serrated face of the chaser and the other in proximity thereto on the back of the chaser. In testimony whereof I afiix my signature in presence of two witnesses.

HENRY L. FISHER.

v Witnesses: .Gno. H. RUssELL,

Am. N. RUSSELL. 

